A vehicular side structure of type above is well known, as disclosed in JP-A-2003-118634. The side structure disclosed in JP-A-2003-118634 includes a rail assembly including an inner member (an inner panel) defining an inner wall of the rail assembly. The rail assembly also includes an outer member (a pillar reinforcement member) overlying an exterior surface of a portion of the inner member to provide the rail assembly with a closed cross-section. The side structure also includes an arch assembly extending laterally of a vehicle and connected to the rail assembly. A roof panel is disposed above the arch assembly to cover the arch assembly.
The arch assembly includes upper and lower members which define a closed cross-section. The arch assembly of closed cross-section is spot welded to the rail assembly of closed cross-section to rigidify the vehicular side structure.
As for the side structure disclosed in JP-A-2003-118634, since the outer member of the rail assembly overlies the portion of the inner member of the rail assembly, a boundary between the portion of the inner member and the remaining portion of the inner member defines a boundary between the outer member and the inner member. Thus, to provide the roof panel atop the inner and outer members of the rail assembly, a flange of the roof panel is welded to both of the inner and outer members astride the boundary between the inner and outer members.
However, due to molding or fabrication tolerances of the inner and outer members, it is difficult to accurately form the boundary between the inner and outer members in assembling the inner and outer members together. It is thus difficult to accurately position the roof panel relative to the inner and outer members during a process of welding the flange of the roof panel to both of the inner and outer members astride the boundary therebetween.
As for the side structure disclosed in JP-A-2003-118634, further, the arch assembly of closed cross-section, the rail assembly of closed cross-section and the roof panel are spot welded to one another with the roof panel, the arch assembly and the rail assembly overlapping. This spot welding may be done with four members, that is, the inner member, the outer member, the upper member and the roof panel overlapping or with four members, that is, the inner member, lower member, the upper member and the roof panel overlapping. In this regard, typically, it is desirable to limit the number of sheet members to three when spot welding the sheet members to one another.